Absorption Cooling Air Compressor System

ABSTRACT

An integrated absorption refrigeration and air compressor system comprising an air compressor system for compressing air and an absorption system for cooling air. The air compressor system comprises at least one air filter for cleaning entering air, a shut-off valve and plurality of bypass valves for blocking air from entering the absorption system, a compressor for increasing the pressure of the air, an after-cooler for cooling the air, a receiver for storing the air, and a pressure regulation valve for delivering the compressed air to end users. The integrated system also comprises an absorption system for cooling air. The absorption system comprises an evaporator for vaporizing air, an absorber for creating a strong absorbent solution, a pump for pumping the solution through the system, an economizer for heating the solution, a generator for creating steam and weakening the solution, a condenser for condensing the steam into a liquid.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX

Not Applicable

TECHNICAL FIELD

The disclosed embodiments generally relate to air compressor systems and, more particularly, to air compressor systems used in industrial manufacturing plants, instruments, and other applications.

DESCRIPTION OF THE RELATED ART

An air compressor system decreases the volume and increases the pressure of a quantity of air by mechanical means. Compressed air has a lot of potential energy because air expands rapidly upon the removal of external pressure. The force of compressed air can be used to power tools and devices that use air.

FIG. 2 is an illustration of the components of a conventional air compressor system in the prior art. Typical prior art air compressor system 200 is shown in FIG. 2 of the drawings. Air filter 202 is typically located at the entrance of prior art air compressor system 200. Air filter 202 is located upstream of compressor 204 and filters out particles in the air to protect the compressor from physical damage. Compressors use volumetric or centrifugal compression to increase the air pressure so that it reaches the required level needed. The compressor may be lubricant free or lubricant injected. In the Figure, air separator 208 is located downstream of air compressor 204 and functions to separate the air and the lubricant. An air separator is not a necessary component in lubricant free compressors. Lubricant cooler 206 cools lubricants to a lower temperature range (typically in the range of between 30° C. to 50° C.) to ensure the safe and efficient operation of the compressor. If a lubricant injected compressor is used, coalescing separator 210 is included to separate the lubricant from the air and thus prevent it from being trapped in after-cooler 212. Compressed air is cooled by after cooler 212 to a lower temperature range (typically within the range of 30° C. to 50° C.) in order to minimize the capacity of the dryer and associated operating costs. After passing through the after-cooler, the air becomes saturated. Cooling is typically accomplished using air or water cooled heat exchangers. Moisture separator 214 removes condensed liquid from the air stream. Dryer 216 removes excess moisture in the system to satisfy the process moisture requirement. Particulate air filter 218 is generally installed downstream of dryer 216 to prevent adsorbed matter from entering the distribution system. Since air is often saturated after passing through air filter 218, any temperature drop along the pipe has the potential to cause condensation (and thus create issues during industry processes). Air receiver 220 stores enough air to minimize pressure fluctuations if the load changes, and heater 222 is equipped to heat the air and prevent condensation in the duct. Air pressure regulation valve 224 regulates the air pressure at a level required for the operation of the process equipment.

The previously described compressor system is typical of air compressor systems in the prior art. Such systems have drawbacks. A major issue of prior art air compressor systems like the one described is that high temperatures are needed and the amount of moisture present is excessive. The compressor consumes more power and does not operate very efficiently under these conditions. In fact, when employed in summer weather conditions, it must be sized up to 10% higher to meet the required capacity. In addition, the filter, dryers, and separators of prior art compressor systems are also affected by excessive pressure losses. These pressure losses can equal up to 30% of the compressor head and consume up to 30% of the total compressor power. The dryer and after cooler also consume an excessive amount of energy in prior art systems (or as much as 15% of the total compressor power). The inefficiency of the compressor is related to the low compressed air temperature. In order to remove moisture, the compressed air temperature is often cooled as low as 21° C., thus reducing the air volume by as much as 10%. Thus, in prior art systems, up to 10% of the compressed air is wasted. Prior art compressed air systems (excluding the distribution system) thus often use 20% to 45% more power than is actually necessary.

Ideally, a system would be devised that can resolve the system drawbacks in the prior art. However, at the current time there is no known method or system which accomplishes this objective.

SUMMARY OF THE INVENTION

The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to an embodiment of the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.

In one embodiment, an absorption cooling air compressor system is proposed. The proposed system is comprised of an integrated absorption and air compressor system. The integrated system comprises an air compressor system for compressing air and an absorption system for cooling air. The air compressor system comprises, in series, at least one air filter for cleaning air entering the system. A plurality of valves are located downstream of the at least one air filter to keep air from entering the absorption system. One of the plurality of valves, a shut-off valve, allows air that is at a temperature above freezing to enter the absorption system. The shut-off valve ensures that freezing air is not cycled through the absorption system. The air compressor system further comprises an air compressor located downstream of the at least one air filter and configured to compress air that enters it. An after-cooler is located downstream of the compressor for cooling the air, a receiver downstream of the after-cooler for storing the air, and a pressure regulation valve located downstream of the receiver for delivering the compressed air at the desired pressure to end users. In some embodiments, variable frequency drives are connected to the fan and compressor and are configured to modulate their speeds. In other embodiments, the system comprises only one VFD connected to either the fan or compressor.

The integrated absorption and air compressor system also comprises an absorption system for cooling air. The absorption system is cyclical in function and comprises an evaporator located on the airflow line downstream of the at least one air filter and shut-off valve and configured to vaporize water and entering air, an absorber in communication with said evaporator and configured to mix the vaporized water with an absorbent material to form a strong absorbent solution, a pump in communication with the absorber for pumping the solution through the system, an economizer in communication with said pump and absorber and configured to heat the solution, and a generator in communication with said economizer and configured to create steam and weaken the solution. The weakened solution then cycles back through the economizer and the absorber, while the steam is cycled through a condenser. The condenser is configured in communication with the generator and condenses the steam into a liquid that is then cycled through at least one expansion valve and back through the absorption system. In some embodiments, the liquid is also cycled through a deep dryer located on the airflow line of the absorption system downstream of the after cooler.

In embodiments in which the compressor is lubricant injected, the integrated air compressor and absorption system comprises an oil cycle system. In such embodiments, an oil separator and coalescing filter are configured in-line downstream of the compressor for the purpose of separating the compressor oil from the air and to filter the air, respectively. Embodiments that include an oil cycle system also include an oil cooler configured in connection with the compressor, generator, and oil separator that cools the oil.

ADVANTAGES

Accordingly, it is one aspect of an embodiment to reduce the moisture content in the air stream and inlet temperature. As a result, annual energy consumption is reduced by 5% to 10%.

It is another aspect of an embodiment to eliminate the need for an after cooler, moisture separator, and heaters.

It is a further aspect of an embodiment to install an H-per filter upstream of the compressor to reduce both the equipment costs and the required compressor head. This has the potential to reduce energy consumed by the compressor by 10 to 20% and by up to 40% in applications that require very dry air.

It is yet a further aspect of an embodiment to reduce the system pressure by installing an evaporator and fan upstream of the compressor. When dry air is needed, the embodiments of the system can save compressor energy by up to 40%. When it is implemented in large compressed air plants, the proposed embodiment effectively cools buildings.

BRIEF DESCRIPTION OF THE DRAWINGS

It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the following figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Advantages, features, and characteristics of the present disclosure, as well as methods and functions of related elements of structure, and the combination of parts and economies of manufacture, will become apparent upon consideration of the following description and claims with reference to the accompanying drawings, all of which form a part of the specification, wherein like reference numerals designate corresponding parts in the various figures, and wherein:

FIG. 1 is a schematic diagram of the system embodying the principles of the absorption cooling air compressor system used for compressing air.

FIG. 2 is a schematic diagram of an air compressor system in the prior art.

FIG. 1 DRAWINGS REFERENCE NUMERALS

-   100 Absorption Cooling Air Compressor System -   102 Air Inlet Filter -   104 H-per Filter -   106 Shut-off Valve -   108 Evaporator -   110 Bypass Valve I -   112 Expansion Valve I -   114 Fan -   116 Compressor -   118 VFD I -   120 VFD II -   122 Oil Separator -   124 Coalescing Filter -   126 Generator -   128 Bypass Valve 2 -   130 Economizer -   132 Absorber -   134 Pump -   136 Oil Cooler -   138 Condenser -   140 After Cooler -   142 Deep Dryer -   144 Receiver -   146 Pressure Regulation Valve -   148 Expansion Valve II -   150 Pressure Sensor I -   152 Temperature Sensor I -   154 Temperature Sensor II -   156 Liquid Level Sensor I -   158 Liquid Level Sensor II -   160 Temperature Sensor III -   162 Pressure Sensor II -   164 Temperature Sensor IV

FIG. 2 PRIOR ART DRAWINGS REFERENCE NUMERALS

-   200 Prior Art Air Compressor System -   202 Air Filter -   204 Air Compressor -   206 Air Separator -   208 Lubricant Cooler -   210 Coalescing Separator -   212 After Cooler -   214 Moisture Separator -   216 Dryer -   218 Air Filter -   220 Air Receiver -   222 Heater -   224 Air Pressure Regulator

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosed is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “attached,” “connected,” “supported,” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “attached,”, “connected”, “supported”, “communicated” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, and supports. Further, “connected” and “communicated” is not restricted to physical or mechanical connections.

FIG. 1 shown below illustrates an embodiment of the disclosed absorption cooling air compressor system. It is shown that absorption cooling air compressor system 100 is comprised of air inlet filter 102, H-per filter 104, shut off valve 106, evaporator 108, bypass valve I 110, expansion valve 112, fan 114, compressor 116, variable frequency drive I (VFD I) 118, variable frequency drive II (VFD II) 120, oil separator 122, coalescing filter 124, generator 126, bypass valve II 128, economizer 130, absorber 132, pump 134, oil cooler 136, condenser 138, after-cooler 140, deep dryer 142, receiver 144, pressure regulation valve 146, and expansion valve II 148, pressure sensor I 150, temperature sensor I 152, temperature sensor II 154, liquid level sensor I 156, liquid level sensor II 158, temperature sensor III 160, pressure sensor II 162, and temperature sensor IV 164.

Absorption cooling air compressor system 100 is comprised of an integrated absorption air compressor system. In the embodiment illustrated in FIG. 1, air that enters absorption cooling air compressor system 100 first enters air inlet filter 102, a medium grade filter configured upstream of H-per filter 104 and configured to remove mechanical dirt from the incoming air stream. (In other embodiments, air inlet filter 102 may be a filter of a differing grade). In the embodiment shown in the Figure, the entering air then continues along the airflow line to H-per filter 104, a high performance filter that also removes dirt and particles from the airstream and is configured downstream of air inlet filter 102 on the airflow line. The particular type and use of the H-per filter selected is dependent on the types of applications with which absorption cooling air compressor system 100 is used. While illustrated in the embodiment in FIG. 1, H-per filter 104 is not included in all embodiments. Generally, H-per filter 104 is included in absorption cooling air compressor system 100 in applications in which very dry air is needed such as for products in the pharmaceutical industry. In the illustrated embodiment, air filtered by H-per filter 104 proceeds to shut-off valve 106. Shut-off valve 106 is configured on the airflow line of the absorption system upstream of evaporator 108. Valve 106 does not let air at a temperature at or lower than 0° C. (adjustable) enter into the absorption system. It is configured to remain open to let air that is at a temperature above 0° C. enter evaporator 108 and continue through the absorption system. Filters 102 and 104 and evaporator 108 function to clean and cool the air so that it is moisture-free before it enters the compressor. Air that passes through shut-off valve 106 enters into evaporator 108 and into the absorption system. Air that does not enter the absorption system continues through the air compressor system airflow line by bypassing evaporator 108 through bypass valve I 110 and continues on to compressor 116.

In the illustrated embodiment, supply fan 114 is located on the airflow line downstream of evaporator 108. It functions to pull outside air into the system through air inlet filter 102 and H-per filter 104. Notably, supply fan 114 is not included such as in (but not limited to) embodiments that do not include an H-per filter. In embodiments in which the supply fan is included as part of the configuration like that shown in FIG. 1, the fan may also be equipped with at least one variable frequency drive (such as VFD I 118 shown here). VFD I 118 controls the fan speed so that the inlet pressure set point is zero or has a slightly positive pressure. The pressure set point is measured by pressure sensor I 150. In yet other embodiments, however, VFD I 118 is not included. An example of a situation in which VFDs are not included as part of the configuration of absorption cooling air compressor system 100 (but is not limited to this example) include when the compressor has a constant and high load or when the compressor is not configured with a VFD. In the embodiment presented in FIG. 1, compressor 116 is configured in connection with VFD II 120. The configuration illustrated in the FIG. 1s the most energy efficient and best controls the air humidity of the compressed air. When included in the embodiment, variable frequency drive 120 is modulated to maintain the pressure set point as measured by pressure sensor I 150. The continuous modulation of the speed results in a lower air pressure and significant compressor energy savings.

As shown in the illustration in FIG. 1, compressor 116 is a lubricant injected compressor and is thus connected on the air compression system airflow line in communication with an oil cycle system comprising oil separator 122, oil cooler 136, and also involves generator 126. Oil cooler 136 is configured in connection with compressor 116 and generator 126 and functions to cool the oil temperature of oil from the compressor to below its set point. In an embodiment, oil cooler 136 is a forced air cooler, while in other embodiments it may be a water cooler, or other type of heat exchanger. Oil cooler 136 can be controlled via on/off control or speed modulation. In the embodiment illustrated in FIG. 1, oil separator 122 is configured on the air compressor airflow line downstream of compressor 116 and upstream of coalescing filter 124. As part of the oil cycle, it functions to separate oil from the airstream. Oil that is separated out by oil separator 122 is returned to oil cooler 136. Compressor 116 is configured to increase the air pressure so that it reaches the level required to enable air compressor system 100 to provide the amount of air required. In some embodiments, compressor 116 is a constant speed compressor that is turned on and off based on the pressure set point. This pressure set point is measured by pressure sensor II 162. In other embodiments, compressor 116 may be a multiple piston compressor controlled to maintain the required air pressure level based on measurements collected by air pressure sensor I 150. In embodiments in which compressor 116 is not lubricant injected, oil cooler 136 and oil separator 122 are not needed as part of the configuration of system 100.

In the illustration, coalescing filter 124 is configured on the compressor airflow line between oil separator 122 and generator 126 and is configured to remove lubricant from the compressed air stream. In other embodiments, especially those in which compressor 116 is not lubricant injected, coalescing filter 124 may not be included in the configuration of system 100. As shown in the illustration in FIG. 1, air exiting the compressor continues along the air compressor system airflow line to after-cooler 140 by bypassing generator 126 via bypass valve II 128. The valve is controlled by the temperature set point of generator 126. Temperature sensor II 154 is configured inside of generator 126 and determines this set point.

In the illustrated embodiment, after-cooler 140 is configured on the air compressor airflow line between generator 126 and deep dryer 142. The after-cooler functions to cool air that has been compressed to the desired level. Although the embodiment illustrated in FIG. 1 includes deep dryer 142, said deep dryer is not necessary in all embodiments of absorption cooling air compressor system 100. When included in the system, deep dryer 142 is configured on the airflow line between after-cooler 140 and receiver 144. It functions to remove vapor from the compressed air as needed and is typically used in applications in which system 100 needs to produce very dry air. Deep dryer 142 can cool the compressed air to as low as 5° C. (adjustable). At this low temperature, the compressed air contains almost no moisture. In the illustration in the Fig., temperature sensor III 160 is configured downstream of deep dryer 142 on the airflow line and is configured to measure the temperature of the air stream after air exits dryer 142. Receiver 144 is configured downstream of after-cooler 140 (and in some embodiments downstream of the deep dryer) and functions as a reservoir for storing the air. Pressure sensor II 162 is configured in communication with receiver 144 and measures the pressure of the airstream. Air exiting system 100 goes through pressure regulation valve 146. Valve 146 is configured downstream of receiver 144 and regulates the amount of air delivered to the end users.

Air that enters system 100 that is at a temperature above 5° C. enters evaporator 108 and continues through the absorption system before it goes through the air compressor system. The absorption system cycle of system 100 comprises evaporator 108, absorber 132, pump 134, economizer 130, generator 126, and condenser 138. The absorption system also comprises a plurality of expansion valves and liquid and temperature sensors. Incoming air that is allowed to enter into evaporator 108 (by valve 106) is cooled to about 5° C. (adjustable) in order to ensure that it has a high density and low moisture content. In the illustrated embodiment, evaporator 108 is located on the airflow line downstream of shut-off valve 106 and air filters 102 and 104. Absorber 132 is configured in connection along the absorption cycle with evaporator 108. Water vaporized in the economizer proceeds to absorber 132 where it mixes with an absorbent solution (for example LiBr). In absorber 132, the weak solution absorbs steam to form a strong solution. This strong solution is then pumped into economizer 130 and generator 126 by pump 134. Pump 134 is configured in communication with absorber 132 and economizer 130. It primarily functions to recirculate the strong solution from absorber 132 to generator 126. The speed and on/off status of pump 134 is determined by the liquid level in absorber 132. This liquid level is measured by liquid level sensor 158 which in FIG. 1 is located inside absorber 132.

Economizer 130 is configured on the absorption cycle in communication with absorber 132 and generator 126 and is operable to recover heat from said weak solution. The heat recovery reduces the liquid circulation and improves the operating performance of absorber 132. Generator 126 is configured on the absorption cycle line in communication with economizer 130. The generator generates steam as well as a weak absorbent solution from the high temperature air and oil streams (mixture of LiBr and H₂O). Generator 126 also reduces the temperature of the compressed air and oil. The weakened LiBr solution then cycles back through economizer 130 and absorber 132 while the generated steam is passed through condenser 138. Condenser 138 cools the steam to the temperature setpoint determined by temperature sensor IV 164. The condensed steam then cycles through deep dryer 142 (when included in the embodiment of system 100) after passing through expansion valve 2 148, or goes to evaporator 108 after passing through expansion valve 112. The expansion valves are configured on the absorption cycle line in communication with condenser 138 and lowers the pressure of the liquid produced from the condenser. Expansion valve 112 is configured to maintain the supply air temperature at a set point of 5° C. (adjustable).

It will be apparent to those skilled in the art that various modifications can be made in the system for compressor air without departing from the scope or spirit of the given embodiment. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure of this application. 

What is claimed is:
 1. An integrated absorption refrigeration and air compressor system for compressing and cooling air, said system comprising: an air compressor system, said air compressor system comprising: at least one air filter for filtering said air; at least one valve downstream of said air filter for keeping said air within said air compressor system; a compressor downstream of said plurality of valves for compressing said air; an after-cooler downstream of said compressor for cooling said air; a receiver downstream of said after-cooler for storing said air; a pressure regulator valve downstream of said after-cooler for regulating the amount of said air that exits said system; an absorption system, said absorption system of the type configured to operate on a continuous absorption cycle using an absorbant, said absorption system comprising: an evaporator for converting said air to a vapor; an absorber for creating a strong solution from said vapor and said absorbant; at least one pump for pumping said solution through said absorption system; an economizer for recovering heat from said strong solution; a generator for generating steam and a weak absorbant solution from said strong solution; a condenser for condensing said weak vapor absorbant from said generator into a liquid for recycling through said absorption cycle.
 2. The integrated absorption refrigeration and air compressor system of claim 1, wherein said at least one air filter further comprises an H-per filter.
 3. The integrated absorption refrigeration and air compressor system of claim 1, wherein said at least one air filter further comprises an inlet air filter.
 4. The integrated absorption refrigeration and air compressor system of claim 1, further comprising a supply fan downstream of said evaporator and configured to pull said air through said at least one filter and evaporator
 5. The integrated absorption refrigeration and air compressor system of claim 4, further comprising at least one VFD in connection with and configured to control the speed of said supply fan and compressor.
 6. The integrated absorption refrigeration and air compressor system of claim 1, wherein said compressor is lubricant injected.
 7. The integrated absorption refrigeration and air compressor system of claim 6, further comprising an oil cycle system in communication with said lubricant injected compressing comprising an oil cooler configured to cool said lubricant, and an oil separator configured to separate said lubricant from said air.
 8. The integrated absorption refrigeration and air compressor system of claim 6, further comprising a coalescing filter downstream of said compressor and configured to remove lubricant from said stream of air.
 9. The integrated absorption refrigeration and air compressor system of claim 1, further comprising a deep dryer downstream of said after-cooler and configured to lower the temperature and reduce the moisture of said air.
 10. The integrated absorption refrigeration and air compressor system of claim 1, wherein said compressor is a multiple piston compressor.
 11. The integrated absorption refrigeration and air compressor system of claim 1, wherein said compressor is a constant speed compressor configured to turn on and off based on the pressure set point. 